|
| |
Vitamin B12
(cobalamin)
DESCRIPTION/FUNCTION
- Cobalamin is classified as a B-vitamin. It is involved in the metabolism of
single-carbon fragments; essential for biosynthesis of nucleic acids,
nucleoproteins, and red blood cells; role in metabolism of nervous tissue;
involved with folate metabolism; related to growth.
DRI (RDA or AI for Adults)
- Adults: 2.4 mcg.
- Pregnancy: 2.6 mcg.
- Lactation: 2.8 mcg.
MAJOR SOURCES
- Liver, clams, kidney, oysters, seafood, beef, lamb, lowfat yogurt.
- Animal products (meat, poultry, fish, eggs) provide
primarily two forms of B12: adenosylcobalamin and hydroxocobalamin. Dairy
products (milk, yogurt, cheese) do not contain as much B12 (mostly
methylcobalamin and hydroxocobalamin).
- Cyanocobalamin, the form commonly used in
supplements, can be converted by the body into other forms of B12, including
hydroxocobalamin.
- Vegans
require supplement.
MAINTENANCE/THERAPEUTIC RANGE
POSSIBLE THERAPEUTIC APPLICATIONS
- Cancer
- Chronic fatigue syndrome
- Coronary heart disease
- High homocysteine
- HIV/AIDS
- Infertility (male)
- Memory loss
COMMENTS
- Vitamin B12 is stored in the liver, mostly as adenosylcobalamin. B12 works
with folic acid in reducing homocysteine, a risk factor for heart disease. Two
enzymatic reactions in humans have been identified requiring vitamin B12. One
coenzyme is adenosylcobalamin and the other is methylcobalamin. Vitamin B12
offers protection to those who react to sulfites in food and wine.
CAUTIONS
- None significant. Avoid cyanocobalamin if you have Leber’s optic atrophy.
|